Self-Destruct (5e Spell)

From D&D Wiki

You pour a small part of your life force into a gem, turning it into an explosive device. Upon doing so you deduct 1d4 from your maximum HP total. This gem can be activated by its creator, and upon doing so it releases all the energy contained within. Each creature in a 10-foot radius, centered on the gem, must succeed on a Dexterity saving throw. A target takes 8d12 force damage on a failed save, or half on a success.

This gem can also be embedded in a creature's body (referred to as the host) and connected to its life essence (which requires 2 hours of surgery, and a DC 16 Medicine check. If you fail this check, the gem is not connected to the life force but remains inside the host). Once connected to the host's life force, the gem begins feeding off of the essence and grows stronger, making the host lose 1d20+10 off their total maximum HP, and gaining 3d12 extra damage, as well as 10-feet being added to the explosion radius.

If detonated inside a host, the explosion ignores any resistances or immunities that the host may have. The host can activate the gem at will, even when unconscious.

At the beginning of each week the gem absorbs more of the host's life force, gaining an additional 2d12 force damage as well as an extra 10-feet to its explosions radius.

Any host killed by this spell cannot be resurrected as its very essence is annihilated by the gem (only applies if the gem was connected to its life essence).